Chemistry SL Paper 1A, May 2025, TZ2

A beaker contains a clear, colourless solution of potassium nitrate in water. What is the type of mixture and the best method of obtaining the solid salt from it? A. heterogeneous, by filtration B. heterogeneous, by evaporation C. homogeneous, by filtration D.…

Which property is the same for ammonia molecules containing deuterium, $\ce{ND3}$, and ordinary ammonia molecules, $\ce{NH3}$? A. Molar mass B. Molecular geometry C. Density of the gas at STP D. Rate of diffusion

When an electric discharge is passed through hydrogen gas at low pressure, the emitted light forms a line emission spectrum: a series of separate, sharp lines that converge as the frequency increases, rather than a continuous band of colour. What does this…

What is the maximum number of electrons that can occupy the n = 4 main energy level? A. 8 B. 16 C. 18 D. 32

What is the empirical formula of a compound with the following composition by mass? Element C H O Percentage by mass 54.5 % 9.1 % 36.4 % A. $\ce{C6HO4}$ B. $\ce{C4H8O}$ C. $\ce{C2H4O}$ D. $\ce{C4H8O2}$

What is the charge of the monatomic ion usually formed by the element with the following electron configuration? $\ce{[Ne] 3s^2 3p^4}$ A. 2+ B. 2− C. 4+ D. 6+

Which molecule is polar? A. $\ce{BF3}$ B. $\ce{NF3}$ C. $\ce{CCl4}$ D. $\ce{C2H4}$

A paper chromatogram is shown. The distances marked were measured along the paper. What is the retardation factor, $R_F$, of compound Y? A. 0.40 B. 0.60 C. 0.70 D. 1.67

Metallic bonding results from the attraction between a lattice of cations and delocalized electrons. Which of these group 1 metals has the strongest metallic bonding? A. Cs B. Rb C. K D. Na

Which monomer produces this addition polymer? A. $\ce{CH2=CHCH2CH3}$ B. $\ce{CH3CH=CHCH3}$ C. $\ce{CH2=C(CH3)2}$ D. $\ce{CH2=CHCH=CH2}$

The diagram shows an outline of the periodic table split into four labelled regions. Each labelled region corresponds to one block of elements. Which region contains the f-block elements, the lanthanides and actinides? A. Region A B. Region B C. Region C D.…

Why is the first ionization energy of sulfur greater than that of magnesium? A. The outer electrons of sulfur are further from the nucleus. B. Sulfur atoms have more occupied main energy levels. C. Sulfur atoms have a greater nuclear charge, while the…

What is the oxidation state of chlorine in $\ce{Cl2O7}$? A. $-7$ B. $+3.5$ C. $+7$ D. $+14$

Butanone, $\ce{CH3COCH2CH3}$, has the structure shown. One of the following four compounds shares its molecular formula, $\ce{C4H8O}$, with butanone. Which compound is this structural isomer of butanone? A. $\ce{CH3COCH2CH2CH3}$ B. $\ce{CH3CH2CH2CHO}$ C.…

The energy profile below was recorded for a reaction. Which pair of statements is consistent with it? In each option the first statement compares the enthalpy of the products with that of the reactants and the second gives the sign of $\Delta H$. A. products…

A liquid fuel was burned in a spirit burner and the heat released was used to warm water in a metal calorimeter, as shown. Quantity Value Amount of fuel burned 0.0250 mol Mass of water 150 g Initial temperature of water 19.5 °C Final temperature of water 31.5…

What is the coefficient of oxygen when the equation for the complete combustion of butan-1-ol is balanced using the smallest whole numbers? The unbalanced equation is $\ce{C4H9OH + O2 -> CO2 + H2O}$. A. 4 B. 6 C. 7 D. 13

What are the limiting reactant and the theoretical yield of hydrogen when 0.30 mol of aluminium reacts with 0.60 mol of hydrochloric acid? $\ce{2Al(s) + 6HCl(aq) -> 2AlCl3(aq) + 3H2(g)}$ In each option the limiting reactant is given first and the theoretical…

Which are units for rate of reaction? A. $\mathrm{s\,mol^{-1}\,dm^{3}}$ B. $\mathrm{mol\,dm^{-3}\,min}$ C. $\mathrm{mol\,dm^{-3}\,min^{-1}}$ D. $\mathrm{mol\,min^{-1}}$

Which changes increase the rate of the reaction? $\ce{CaCO3(s) + 2HCl(aq) -> CaCl2(aq) + H2O(l) + CO2(g)}$ I. Grinding the calcium carbonate into a fine powder II. Using a larger volume of hydrochloric acid of the same concentration III. Warming the…

Increasing the temperature of a reaction mixture increases the rate of reaction. What is the best explanation for this? A. A greater proportion of collisions occur with energy greater than or equal to the activation energy. B. A greater proportion of…

The following system is at equilibrium. $\ce{H2(g) + I2(g) <=> 2HI(g)}$ $K = 54$ What is the value of the equilibrium constant, K, for the reaction $\ce{2HI(g) <=> H2(g) + I2(g)}$? A. $-54$ B. $\dfrac{1}{54}$ C. $\sqrt{54}$ D. $\dfrac{1}{\sqrt{54}}$

The container holding the equilibrium mixture below is compressed to half its volume while the temperature is kept constant. Which row gives the change in the amount of $\ce{PCl5}$ and the effect on the equilibrium constant, $K$?…

What is the conjugate acid of the hydrogen phosphate ion, $\ce{HPO4^2-}$? A. $\ce{PO4^3-}$ B. $\ce{H2PO4-}$ C. $\ce{H3PO4}$ D. $\ce{HPO3^2-}$

Which solution has a pH of 11.0 at 298 K? A. $10^{-3}\ \mathrm{mol\,dm^{-3}}$ $\ce{KOH(aq)}$ B. $10^{-11}\ \mathrm{mol\,dm^{-3}}$ $\ce{KOH(aq)}$ C. $10^{-3}\ \mathrm{mol\,dm^{-3}}$ $\ce{NH3(aq)}$ D. $10^{-3}\ \mathrm{mol\,dm^{-3}}$ $\ce{HCl(aq)}$

What is the main reason why nitric acid has a lower pH than ethanoic acid of the same concentration? A. Nitric acid is an oxidizing agent. B. Nitric acid ionizes to a greater extent in water. C. The conjugate base of nitric acid is stronger than that of…

In which compound does nitrogen have an oxidation state of +3? A. $\ce{NH3}$ B. $\ce{HNO2}$ C. $\ce{NO2}$ D. $\ce{HNO3}$

Zinc displaces copper from aqueous copper(II) sulfate solution, as shown in the voltaic cell below. Which row correctly gives the sign and the electrode type of the zinc electrode in this cell? In each option the sign is given first and the electrode type…

Which change represents oxidation of the functional group? A. $\ce{CH3COCH3 -> CH3CH(OH)CH3}$ B. $\ce{CH3CH(OH)CH3 -> CH3COCH3}$ C. $\ce{CH3CH2COOH -> CH3CH2CHO}$ D. $\ce{CH3CH=CH2 -> CH3CH2CH3}$

Which equation represents a propagation step in the radical substitution of ethane by bromine? A. $\ce{Br2 -> 2Br•}$ B. $\ce{•C2H5 + Br• -> C2H5Br}$ C. $\ce{C2H6 + Br• -> C2H5Br + H•}$ D. $\ce{•C2H5 + Br2 -> C2H5Br + Br•}$